# How to replace the row of an array by the row of another array with numpy

Published: January 17, 2019

Examples of how to replace array line by another array line with numpy:

### Array of same size

let's try to replace array N line 2 by array M line 2:

````>>> import numpy as np`
`>>> M = np.array([[2,7,1],[3,3,1],[5,4,2],[0,1,8]])`
`>>> N = np.zeros((6,3))`
`>>> N[2,:] = M[2,:]`
`>>> N`
`array([[ 0.,  0.,  0.],`
`       [ 0.,  0.,  0.],`
`       [ 5.,  4.,  2.],`
`       [ 0.,  0.,  0.],`
`       [ 0.,  0.,  0.],`
`       [ 0.,  0.,  0.]])`
```

### Array of different sizes (N column > M column)

if dimension 2 of array M is not the same dimension that N:

````>>> import numpy as np`
`>>> M = np.array([[2,7,1],[3,3,1],[5,4,2],[0,1,8]])`
`>>> N = np.zeros((6,4))`
`>>> M_dim_2 = M.shape[1]`
`>>> N_dim_2 = N.shape[1]`
`>>> M_dim_2`
`3`
`>>> N_dim_2`
`4`
`>>> if N_dim_2 > M_dim_2:`
`...     N[2,:M_dim_2] = M[2,:] `
`... `
`>>> N`
`array([[ 0.,  0.,  0.,  0.],`
`       [ 0.,  0.,  0.,  0.],`
`       [ 5.,  4.,  2.,  0.],`
`       [ 0.,  0.,  0.,  0.],`
`       [ 0.,  0.,  0.,  0.],`
`       [ 0.,  0.,  0.,  0.]])`
```

### Array of different sizes (N column < M column)

````>>> N = np.zeros((6,2))`
`>>> N_dim_2 = N.shape[1]`
`>>> N_dim_2`
`2`
`>>> if N_dim_2 < M_dim_2:`
`...     N[2,:] = M[2,:N_dim_2] `
`... `
`>>> N`
`array([[ 0.,  0.],`
`       [ 0.,  0.],`
`       [ 5.,  4.],`
`       [ 0.,  0.],`
`       [ 0.,  0.],`
`       [ 0.,  0.]])`
```